Malaysia has recalled its envoy to Pyongyang in an escalating row over the killing of Kim Jong-nam, the half-brother of North Korea's leader Kim Jong-un.
Kim Jong-nam died in mysterious circumstances last week at a Kuala Lumpur airport - police believe he was poisoned while waiting for a flight.
Malaysian police say they are now looking for four North Koreans.
Pyongyang's envoy to Malaysia was also summoned over earlier comments he made.
Despite widespread speculation that North Korea was behind the killing, there has been no definitive evidence and Pyongyang has not issued an official statement yet.
South Korea has accused the North of orchestrating the incident, saying on Monday it was evidence of North Korean "terrorism getting bolder".
Meanwhile a video which apparently shows CCTV footage of the attack on Kim Jong-nam has surfaced and aired on Japanese television.
What has led to the diplomatic spat?
Malaysia was one of very few countries to maintain diplomatic relations with North Korea, but this killing has strained ties.
Malaysia has refused to accede to North Korean demands to release Kim's body into their custody without an autopsy.
It prompted Pyongyang's ambassador to Malaysia, Kang Chol, to accuse Kuala Lumpur on Friday of colluding with "hostile forces", saying that Malaysia had "something to conceal".
This provoked an angry response from the Malaysian foreign ministry which said his accusation was "baseless", adding that it was their responsibility to conduct an investigation as Kim had died on Malaysian soil.
What's happening to Kim's body?
Malaysian authorities are now waiting for the results of its autopsy. Kang Chol said his country would reject the result as it was done without their presence.
Malaysia has also refused to release Kim's body, saying it needs to conduct DNA testing first.
Police are now seeking samples from family members. Kim is believed to have family living in Beijing and Macau.
Malaysian police have said that if there is no claim by next of kin and once they exhaust all avenues for DNA collection, they will hand the body over to the North Korean embassy.
Who has been arrested so far?
Kim is believed to have been attacked in the Kuala Lumpur airport departure hall on Monday by the two women, using some form of chemical.
Fuji TV has aired grainy CCTV footage showing a man resembling Kim Jong-nam approached by a woman at the airport.
Another woman then quickly lunges from behind and wipes his face with a cloth. She is seen wearing a white top emblazoned with the letters "LOL".
The man is then seen seeking assistance from airport staff while gesturing at his face, and is escorted to a room.
Two women, one Indonesian and one Vietnamese, were among the first to be arrested. The Indonesian, named as Siti Aisyah, is said to have told Malaysian police she had been paid to perform what she thought was a prank.
Police have also detained one North Korean suspect, Ri Jong-chol, and said they are looking for four more men, who may have already left the country.
The men have been named as Ri Ji Hyon, 33; Hong Song Hac, 34; O Jong Gil, 55, and Ri Jae Nam, 57.
Who was Kim Jong-nam?
Kim was the first-born son of former North Korean leader Kim Jong-il, who died in 2011.
He was largely estranged from his family, after being passed over for the North Korean leadership in favour of his youngest half-brother.
He went into exile in the early 2000s, spending most of his time in Macau, mainland China and Singapore.
Kim had spoken out in the past against his family's dynastic control of North Korea and in a 2012 book was quoted as saying he believed his younger half-brother lacked leadership qualities.
But he had also said he was not interested in assuming the leadership himself.